Candida albicans is an opportunistic pathogen causing morbidity and mortality in patients with immuno-dysfunction. Multidrug resistant Candida has emerged as significant health problem. The White laboratory is at the forefront in studying the cellular and molecular mechanisms of multidrug resistance in Candida. We propose to further define the transcriptional controls involved in the drug resistant phenotype of a well-defined series of isolates from a single AIDS patient. The specific aims of this proposal are: 1) to identify the transcriptional controls of the MDR1 promoter from the azole-sensitive and azole-resistant isolates, 2) to determine the domains interacting with transcription factors involved in azole-resistance, drug induction and specified environmental states, and 3) to determine if the CAP1p or other transcription factors interact with MDR1 promoter. Promoter deletion analysis will be used to identify the basal level transcription, silencers and enhancers utilized by these promoters. Gel mobility shift assays, competition experiments and DNase I footprint analysis will further define protein:DNA interactions. Finally, characterized transcription factors such as CAP1 will be used in gel mobility shift assays, competition experiments and antibody supershifts to determine the interactions between these factors and the drug resistant MDR1 promoter. This project is designed to generate valuable information that could lead to development of drugs or methods to control multidrug resistance in Candida. In addition, it will further Candida research by being a comprehensive study on the transcriptional controls important in a multidrug resistance phenotype.